Drag of the Venusian Atmosphere by Solar Wind

One of the more efficient mechanisms of volatiles lost in the non-magnetic planets is its drag by solar wind. In this study it is explored this type of erosion for Venus and it is obtained some numerical results leaving from plausible models of degassing and drag. The obtained results from this study are: Venus had degassed, in all its history, of the order of 286.87 TAM of volatiles (1 TAM = 1 Terrestrial Atmospheric Mass = 5.28x1018 kg), i.e., 1.515x1021 kg. Since current mass of the planet's atmosphere is 89.92 TAM the volatiles mass that Venus has lost in the same period is of the order of 196.95 TAM, i.e., 1.04x1021 kg. The drag capacity of the solar wind in the first Ga of the planet's life was very large such that it could drag of the order of 108 TAM if Venus had have it. Degasification did not could compete with the drag that maintains the planet free of volatiles and at the solar wind flowing directly in surface. After this first Ga in the following 3.6 Ga the drag capacity of the solar wind reduced drastically and then the solar wind only could drag at the most of the order of 88 TAM of volatiles. The mass dragged by the solar wind in all the history of Venus fluctuate between 70 and 200 TAM, i.e., between 3.7x1020 kg and 1.06x1021 kg. In last 3.6 Ga the dragged mass by solar wind fluctuate between 11 and 61 TAM and y the last 500 Ma between 0.32 and 0.41 TAM. The lost by other mechanisms fluctuate between 1 and 130 TAM. For the scenarios of more loss the usual mechanisms could not explain the quantity of lost volatiles, for this it is proposed the hypotheses of the Great Impact (the collision of Venus with a body larger than Moon 500 Ma ago) this hypotheses not only explain the lost of volatiles but also other aspects do not understand of Venus, like its slowly and retrograde rotation and the renovation of all its surface 500 Ma ago.